As I said this was for two reasons - it's easy as pie to throw together, and it captures all five of the tastes Sweet, Sour, Salty, Bitter and Umami aka Savoury.

I had no set recipe in mind, and just wanted to find ingredients that complement and contrast each other - so before turning up to the challenge, I went to the Japan Centre on Lower Regent Street to see what appealed. I considered umeboshi, a type of pickled Japanese apricot, for the sour element; katsuobushi hanakatsuo, the flakes of bonito that dance about madly on top of okonimyaki pancakes, for the savoury; and strips of nori seaweed for the salt.

Eventually, I went for buna-shimeji mushrooms, dashi, mirin wine, soy, ikura, shiso leaves and negi onion, and handed over my £15 (ikura particularly is a pricey treat, though worth every penny.

Green & Black's 15:15 Challenge Winner - Shimeji Shiso Pasta

Serves one

100g linguine (I like De Cecco)

1 clump of buna-shimeji mushrooms (aka beech mushrooms)

1 tsp mirin

1 tsp Japanese soy sauce

1 tsp dashi

2 shiso leaves (aka perilla or beefsteak plant)

1 negi (a type of fat spring onion)

Handful of ikura (salmon roe)

1 tbsp olive oil

Put the pasta on to boil.

Slice a half-inch off the bottom of the mushroom clump and discard this piece. Break the mushrooms into small clusters.

Roll the shiso leaves into a "cigar" and shred finely. Shred the spring onion as well.

Heat the oil in a frying pan and sear the mushroom clusters till they brown and crisp slightly on one side only.

Add the soy sauce, dashi, mirin and 2 tbsp of the pasta cooking water and sizzle for another couple of minutes.

Drain the pasta, chuck the mushrooms and their sauce on top, scatter with the salmon roe and the shredded shiso and spring onions. Serve.

*** GREEN & BLACK'S CHOCOLATE COMPETITION ***

[THIS COMPETITION IS NOW CLOSED]

So as you know, I won the 15:15 Challenge and the Chocolate Taste Test so was rewarded with a beautiful red KitchenAid mixer and also a set of Kyle Cathie books. One of the books was the new Green & Black's Ultimate Cookbook which I already owned, so I thought I'd spread the love and run a little competition to win the book and some other chocolate prizes.

Edited by Micar Carr-Hill their Head of Taste, "Ultimate" has recipes for cakes and cookies, cupcakes and cheescakes, puddings and pies, ice creams and even sweets. Contributors include Micah, as well as chefs such as Jose Pizarro, Allegra McEvedy, Omar Allibhoy, and Gizzi Erskine, and top blogger The Ginger Gourmand.

For more on just how fab this book is, see the post by The Catty Life.

Enter this competition to win the prize pictured above comprising:

A copy of the new Green & Black's Ultimate Chocolate Cookbook

An official Green & Black's Apron

A bar of Green & Black's 85% Dark Chocolate

A bar of Green & Black's Smooth and Creamy Milk Chocolate

A bar of Green & Black's Dark Cook's Chocolate

A bar of Green & Black's White Cook's Chocolate

To win this glamourous prize, answer the following question in a comment below.

Q: Is white chocolate chocolate?

Answer using science, pseudo-science, flippancy or humour, and leave your twitter name or email address in the body of the comment.Closing date for entries is midday on Monday 29 November - UK ENTRANTS ONLY (sorry!).

I'm pretty sure white chocolate *kind* of is chocolate, since it's made of cocoa butter, if not actually any cocoa solids...Or maybe from the drained life-blood of wee bespectacled blonde boys.Or something.

White Chocolate is as we all know is a culmination of bleaching good quality cocoa nibs by grinding on the thighs of a thousand virgins, roasting in the fires of vesuvius, before the teardrop of a hormonal unicorn completes the ethereal transformation and produces what we have all come to love 'white chocolate' What is white chocolate Hhmph!

Personally I'm finding this "is white chocolate chocolate" debate very disturbing. It's a racist slippery slope. Next thing you know, green bean noodles will be left all strung out by other noodles and black cod will be barred admission from schools of cod. And where will that all end, other than on my plate?

White Chocolate is not chocolate. It is the Milli Vanilli of the chocolate world.

BTW: I love ume-boshi. I especially love the look on peoples faces when they try and eat a whole one for their first taste ever. It makes me laugh. Why? Beacuse I caused so much merriment when it was done to me this first time I have to pay it forward!

These discussions of the contents of white chocolate do not matter. The point is this: would you ever turn to white chocolate to ease heartache? Would you guiltlessly break a diet to let the tiniest sliver of it dissolve on your tongue? Would you squeeze in a square of it even though you are so full you fear you'll burst? Of course you wouldn't.These are the things that real chocolate makes you do. Therefore, white chocolate doesn't count.

Oh dear… caught up at work and this is post noon. I only want the book. ;)

Still want to put in m two pence. Ahem...

I think white chocolate is chocolate when it’s made with just cocoa butter, sugar, milk and vanilla. The cocoa butter comes from the cocoa bean and it has the texture of dark chocolate and a similar taste to dark chocolate. What else would you call it? Whocolat? Not very appetising… :)